In the world of medical 3D printing, there is a constant drive to innovate and re-imagine what is possible. One of the goals is to one-day 3D print fully functioning human organs. On the path to that goal researchers from the University of Illinois have built a new kind of 3D printer capable of printing complex biological structures out of the same stuff throat lozenges are made of.

With current 3D printing technology, there is a need to have a material that can be heated to a pliable state and then cool with minimal distortion. If you have worked with heating sugar at home, you know that it can easily scorch or crystallize at high temperatures or in liquid form. The Illinois team experimented with different sugar compounds and found that a type of sugar alcohol used in the making of throat lozenges, isomalt, is less inclined to burn or crystalize when heated.

Photo by Troy Comi

Although isomalt still has the opportunity to burn or crystalize they were able to develop a 3D printer that produces the ideal temperature so the isomalt can be extruded through the print nozzle with the correct speed to create smooth hardened stable structures.

“This is a great way to create shapes around which we can pattern soft materials or grow cells and tissue, then the scaffold dissolves away,” said Rohit Bhargava, a professor of bioengineering and director of the Cancer Center at Illinois.

To create the biostructures the 3D printer uses a process called free-form printing. Free-form is kind of like drawing with a VR headset on. As the printer extrudes the material the nozzle moves, the melted material hardens and leaves the self supporting printed structure behind. Since the material they are using is water-soluble and biodegradable, the resulting sugar structure can be used in biomedical engineering, cancer research, and device manufacturing.

“...One possible application is to grow tissue or study tumors in the lab. Cell cultures are usually done on flat dishes. That gives us some characteristics of the cells, but it’s not a very dynamic way to look at how a system actually functions in the body. In the body, there are well-defined shapes, and shape and function are very closely related.” said Rohit Bhargava, a professor of bioengineering and director of the Cancer Center at Illinois.

courtesy of Matthew Gelber

Free-form 3D printing allows researchers to make thin tubes with circular cross-sections that could not be made with conventional polymer 3D printing. When the sugar dissolves, it leaves formations much like blood vessels that can be used to transport nutrients in tissue or to produce channels in microfluidic devices.

The team isn't stopping here though; they are continuing to innovate and test special coatings that will control how and when the sugar structures dissolve. All of this in hopes to one-day develop and use this technology as a building block to 3D print human organs.